Generally, a large amount of heat is generated in an engine of a vehicle, and when a temperature of the engine rises to an appropriate temperature or more, there is a risk of explosion. Therefore, a coolant is circulated in the vicinity of the engine in order to cool the engine, thereby lowering the temperature of the engine. A heated coolant is heat-radiated in a radiator, and a cooling fan is installed in an engine compartment of the vehicle in order to improve a heat radiation effect of the radiator.
The cooling fan maintains a temperature of the coolant in an appropriate condition to prevent overheat of the engine and allow performance of the engine to be optimally exhibited. The cooling fan is mainly driven by a motor.
In a severe cold area, moisture or snow is introduced into the cooling fan, such that freezing of the cooling fan often occurs. Therefore, at the time of the freezing of the cooling fan, the cooling fan is not operated even in a condition in which the cooling fan is turned on.
In the severe cold area, the cooling fan is not generally operated. However, when a driver presses a defrost button in order to remove fog or frost, an air conditioner is operated, such that an air conditioner refrigerant pressure gradually rises. When the air conditioner refrigerant pressure becomes a predetermined pressure or more, it arrives at a region in which the cooling fan should be operated. However, the cooling fan is not operated due to locking of the motor caused by the freezing of the cooling fan. In addition, when a locking time becomes long, the motor is damaged or a fire occurs in the engine compartment in the worst case.
Accordingly, in the conventional case, to prevent the motor from being damaged, the fan motor was locked on the basis of ignition-off time in winter.
However, in the conventional case, logic was too complex and differently applied to various kinds of vehicles, so man-hour was used excessively, and the fan motor was controlled according to ignition-off time so that accuracy was low. Also, when diurnal range is large, the fan motor did not operate, therefore it was not cool to occur driver's dissatisfaction.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.